FIELD OF THE INVENTION
The present invention relates to the determination of properties of threads and more particularly to the determination of strength properties of warp threads in a warp.
The tensile test of textile and industrial yarns has always been an important test in quality control, specifically as regards both staple yarns and filament yarns. This is because the results of the tensile test make it possible to draw conclusions as to the production and therefore reveal production deficiencies; tensile-force and stretch values give indications as to the suitability of the raw material used and allow prognoses for the further processing of the yarn and for the final product.
Tensile tests of this kind are nowadays carried out off-line in a textile laboratory by examining the various yarn batches by random sampling. A known appliance for the tensile testing of yarns and twines is the tensile-testing system USTER TENSORAPID (USTER--registered trademark of Zellweger Uster AG) described in U.S. Pat. No. 4,338,824, and another tensile-strength tester is known from EP-A-O,403,988.
Textile laboratories equipped with modern test appliances are to be found very frequently in spinning mills and somewhat rarely in weaving mills. The reason for their limited use in weaving mills is to be sought in that the known test appliances do not allow testing on warp beams, and in that the strength data of non-sized yarns do not give sufficient indications as to the running behaviour on a specific weaving machine with a specific article. However, the fact that strength data are of interest in weaving mills too is proved by EP-A-O,240,074 which relates to a device for determining the strength properties of weft yarn, by means of which, as a rule, an entire yarn bobbin is always tested and at the same time is also used up.
In contrast, no tensile-strength testers for warp threads which can be integrated into the fabric production process are known, although any warp-thread break leads to a machine stoppage, and therefore the quality control of warp yarns should be of vital interest to any weaving mill.